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diff --git a/Documentation/userspace-api/media/v4l/ext-ctrls-fm-tx.rst b/Documentation/userspace-api/media/v4l/ext-ctrls-fm-tx.rst new file mode 100644 index 000000000..04c997c9a --- /dev/null +++ b/Documentation/userspace-api/media/v4l/ext-ctrls-fm-tx.rst @@ -0,0 +1,181 @@ +.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later + +.. _fm-tx-controls: + +******************************** +FM Transmitter Control Reference +******************************** + +The FM Transmitter (FM_TX) class includes controls for common features +of FM transmissions capable devices. Currently this class includes +parameters for audio compression, pilot tone generation, audio deviation +limiter, RDS transmission and tuning power features. + + +.. _fm-tx-control-id: + +FM_TX Control IDs +================= + +``V4L2_CID_FM_TX_CLASS (class)`` + The FM_TX class descriptor. Calling + :ref:`VIDIOC_QUERYCTRL` for this control will + return a description of this control class. + +``V4L2_CID_RDS_TX_DEVIATION (integer)`` + Configures RDS signal frequency deviation level in Hz. The range and + step are driver-specific. + +``V4L2_CID_RDS_TX_PI (integer)`` + Sets the RDS Programme Identification field for transmission. + +``V4L2_CID_RDS_TX_PTY (integer)`` + Sets the RDS Programme Type field for transmission. This encodes up + to 31 pre-defined programme types. + +``V4L2_CID_RDS_TX_PS_NAME (string)`` + Sets the Programme Service name (PS_NAME) for transmission. It is + intended for static display on a receiver. It is the primary aid to + listeners in programme service identification and selection. In + Annex E of :ref:`iec62106`, the RDS specification, there is a full + description of the correct character encoding for Programme Service + name strings. Also from RDS specification, PS is usually a single + eight character text. However, it is also possible to find receivers + which can scroll strings sized as 8 x N characters. So, this control + must be configured with steps of 8 characters. The result is it must + always contain a string with size multiple of 8. + +``V4L2_CID_RDS_TX_RADIO_TEXT (string)`` + Sets the Radio Text info for transmission. It is a textual + description of what is being broadcasted. RDS Radio Text can be + applied when broadcaster wishes to transmit longer PS names, + programme-related information or any other text. In these cases, + RadioText should be used in addition to ``V4L2_CID_RDS_TX_PS_NAME``. + The encoding for Radio Text strings is also fully described in Annex + E of :ref:`iec62106`. The length of Radio Text strings depends on + which RDS Block is being used to transmit it, either 32 (2A block) + or 64 (2B block). However, it is also possible to find receivers + which can scroll strings sized as 32 x N or 64 x N characters. So, + this control must be configured with steps of 32 or 64 characters. + The result is it must always contain a string with size multiple of + 32 or 64. + +``V4L2_CID_RDS_TX_MONO_STEREO (boolean)`` + Sets the Mono/Stereo bit of the Decoder Identification code. If set, + then the audio was recorded as stereo. + +``V4L2_CID_RDS_TX_ARTIFICIAL_HEAD (boolean)`` + Sets the + `Artificial Head <http://en.wikipedia.org/wiki/Artificial_head>`__ + bit of the Decoder Identification code. If set, then the audio was + recorded using an artificial head. + +``V4L2_CID_RDS_TX_COMPRESSED (boolean)`` + Sets the Compressed bit of the Decoder Identification code. If set, + then the audio is compressed. + +``V4L2_CID_RDS_TX_DYNAMIC_PTY (boolean)`` + Sets the Dynamic PTY bit of the Decoder Identification code. If set, + then the PTY code is dynamically switched. + +``V4L2_CID_RDS_TX_TRAFFIC_ANNOUNCEMENT (boolean)`` + If set, then a traffic announcement is in progress. + +``V4L2_CID_RDS_TX_TRAFFIC_PROGRAM (boolean)`` + If set, then the tuned programme carries traffic announcements. + +``V4L2_CID_RDS_TX_MUSIC_SPEECH (boolean)`` + If set, then this channel broadcasts music. If cleared, then it + broadcasts speech. If the transmitter doesn't make this distinction, + then it should be set. + +``V4L2_CID_RDS_TX_ALT_FREQS_ENABLE (boolean)`` + If set, then transmit alternate frequencies. + +``V4L2_CID_RDS_TX_ALT_FREQS (__u32 array)`` + The alternate frequencies in kHz units. The RDS standard allows for + up to 25 frequencies to be defined. Drivers may support fewer + frequencies so check the array size. + +``V4L2_CID_AUDIO_LIMITER_ENABLED (boolean)`` + Enables or disables the audio deviation limiter feature. The limiter + is useful when trying to maximize the audio volume, minimize + receiver-generated distortion and prevent overmodulation. + +``V4L2_CID_AUDIO_LIMITER_RELEASE_TIME (integer)`` + Sets the audio deviation limiter feature release time. Unit is in + useconds. Step and range are driver-specific. + +``V4L2_CID_AUDIO_LIMITER_DEVIATION (integer)`` + Configures audio frequency deviation level in Hz. The range and step + are driver-specific. + +``V4L2_CID_AUDIO_COMPRESSION_ENABLED (boolean)`` + Enables or disables the audio compression feature. This feature + amplifies signals below the threshold by a fixed gain and compresses + audio signals above the threshold by the ratio of Threshold/(Gain + + Threshold). + +``V4L2_CID_AUDIO_COMPRESSION_GAIN (integer)`` + Sets the gain for audio compression feature. It is a dB value. The + range and step are driver-specific. + +``V4L2_CID_AUDIO_COMPRESSION_THRESHOLD (integer)`` + Sets the threshold level for audio compression freature. It is a dB + value. The range and step are driver-specific. + +``V4L2_CID_AUDIO_COMPRESSION_ATTACK_TIME (integer)`` + Sets the attack time for audio compression feature. It is a useconds + value. The range and step are driver-specific. + +``V4L2_CID_AUDIO_COMPRESSION_RELEASE_TIME (integer)`` + Sets the release time for audio compression feature. It is a + useconds value. The range and step are driver-specific. + +``V4L2_CID_PILOT_TONE_ENABLED (boolean)`` + Enables or disables the pilot tone generation feature. + +``V4L2_CID_PILOT_TONE_DEVIATION (integer)`` + Configures pilot tone frequency deviation level. Unit is in Hz. The + range and step are driver-specific. + +``V4L2_CID_PILOT_TONE_FREQUENCY (integer)`` + Configures pilot tone frequency value. Unit is in Hz. The range and + step are driver-specific. + +``V4L2_CID_TUNE_PREEMPHASIS`` + (enum) + +enum v4l2_preemphasis - + Configures the pre-emphasis value for broadcasting. A pre-emphasis + filter is applied to the broadcast to accentuate the high audio + frequencies. Depending on the region, a time constant of either 50 + or 75 useconds is used. The enum v4l2_preemphasis defines possible + values for pre-emphasis. Here they are: + + + +.. flat-table:: + :header-rows: 0 + :stub-columns: 0 + + * - ``V4L2_PREEMPHASIS_DISABLED`` + - No pre-emphasis is applied. + * - ``V4L2_PREEMPHASIS_50_uS`` + - A pre-emphasis of 50 uS is used. + * - ``V4L2_PREEMPHASIS_75_uS`` + - A pre-emphasis of 75 uS is used. + + + +``V4L2_CID_TUNE_POWER_LEVEL (integer)`` + Sets the output power level for signal transmission. Unit is in + dBuV. Range and step are driver-specific. + +``V4L2_CID_TUNE_ANTENNA_CAPACITOR (integer)`` + This selects the value of antenna tuning capacitor manually or + automatically if set to zero. Unit, range and step are + driver-specific. + +For more details about RDS specification, refer to :ref:`iec62106` +document, from CENELEC. |